DO IT Trial: Vitamin D Outcomes and Interventions in Toddlers - a TARGet Kids! randomized controlled trial

BMC Pediatrics

Volumn 14, Issue 1, 2014, Pages

  Maguire, Jonathon L ^a,b,c,d,f   Birken, Catherine S ^c,d,f   Loeb, Mark B ^g   Mamdani, Muhammad ^a,e   Thorpe, Kevin ^a,e   Hoch, Jeffrey S ^a,e,f,h   Mazzulli, Tony ^d,i   Borkhoff, Cornelia M ^c,f   Macarthur, Colin ^c,d   Parkin, Patricia C ^c,d,f   Abdullah, Kawsari ^j   Anderson, Laura ^j   Carsley, Sarah ^j   Chen, Yang ^j   D'Ascanio, Matthew ^j   Katz Lavigne, Mikael ^j   Kavikondala, Kanthi ^j   Lee, Grace Jieun ^j   Omand, Jessica ^j   Persaud, Navindra ^j   van den Heuvel, Meta ^j   Zabih, Weeda ^j   Baker, Jillian ^j   Barozzino, Tony ^j   Bonifacio, Joey ^j   Campbell, Douglas ^j   Cheema, Sohail ^j   Chisamore, Brian ^j   Danayan, Karoon ^j   Das, Paul ^j   Derocher, Mary Beth ^j   Do, Anh ^j   Dorey, Michael ^j   Freeman, Sloane ^j   Fung, Keewai ^j   Guiang, Charlie ^j   Handford, Curtis ^j   Hatch, Hailey ^j   Jacobson, Sheila ^j   Kiran, Tara ^j   Knowles, Holly ^j   Kwok, Bruce ^j   Lakhoo, Sheila ^j   Lam Antoniades, Margarita ^j   Lau, Eddy ^j   Leung, Fok Han ^j   Loo, Jennifer ^j   Mahmoud, Sarah ^j   Moodie, Rosemary ^j   Morinis, Julia ^j   Naymark, Sharon ^j   Neelands, Patricia ^j   Owen, James ^j   Peer, Michael ^j   Perlmutar, Marty ^j   Pinto, Andrew ^j   Porepa, Michelle ^j   Ramji, Nasreen ^j   Ramji, Noor ^j   Rosenthal, Alana ^j   Saunderson, Janet ^j   Saxena, Rahul ^j   Sgro, Michael ^j   Shepherd, Susan ^j   Smiltnieks, Barbara ^j   Taylor, Carolyn ^j   Weisdors, Thea ^j   Wijayasinghe, Sheila ^j   Wong, Peter ^j   Ying, Ethel ^j   Young, Elizabeth ^j   more..

^a ST MICHAEL'S HOSPITAL   (Canada)

^b ST MICHAEL'S HOSPITAL   (Canada)

^c HOSPITAL FOR SICK CHILDREN   (Canada)

^d UNIVERSITY OF TORONTO   (Canada)

^e UNIVERSITY OF TORONTO   (Canada)

^f UNIVERSITY OF TORONTO   (Canada)

^g MCMASTER UNIVERSITY   (Canada)

^h Pharmacoeconomics Research Unit   (Canada)

ⁱ UNIVERSITY HEALTH NETWORK   (Canada)

^j NONE

more..

Author keywords

Infant; Toddler; Vitamin D deficiency; Vitamin D supplementation

Indexed keywords

25 HYDROXYVITAMIN D; VITAMIN D;

ARTICLE; ASTHMA; CHILD; CONTROLLED STUDY; DISEASE EXACERBATION; DRUG DOSE COMPARISON; DRUG MEGADOSE; FEMALE; HUMAN; HUMAN EXPERIMENT; INFLUENZA A; INFLUENZA B; MALE; NORMAL HUMAN; NOSE SMEAR; PRIMARY HEALTH CARE; RANDOMIZED CONTROLLED TRIAL; RECOMMENDED DRUG DOSE; TREATMENT OUTCOME; VIRAL UPPER RESPIRATORY TRACT INFECTION; VITAMIN BLOOD LEVEL; VITAMIN D DEFICIENCY; VITAMIN SUPPLEMENTATION; WINTER;

ASTHMA; CANADA; CHILD, PRESCHOOL; DIETARY SUPPLEMENTS; DISEASE PROGRESSION; HUMANS; INFANT; RESPIRATORY TRACT INFECTIONS; SEASONS; TREATMENT OUTCOME; VITAMIN D; VITAMINS;

EID: 84896718406     PISSN: None     EISSN: 14712431     Source Type: Journal    
DOI: 10.1186/1471-2431-14-37     Document Type: Article

References (121)

1. Holick MF. Resurrection of vitamin D deficiency and rickets. J Clin Invest 2006, 116:2062-72. 10.1172/JCI29449, 1523417, 16886050.
2. CIHI National Ambulatory Care Reporting System 2005, Ottawa: Canadian Institute for Health Information, CIHI.
3. Maguire JL, Birken CS, O'Connor DL, Macarthur C, Thorpe KE, Mamdani M, Parkin PC. Prevalence and predictors of low vitamin D in urban Canadian toddlers. Pediatr Child Health 2011, 16:e11-e15.
4. Wagner CL, Greer FR. Prevention of rickets and vitamin D deficiency in infants, children, and adolescents. Pediatrics 2008, 122:1142-52. 10.1542/peds.2008-1862, 18977996.
5. CPS Vitamin D supplementation: Recommmendations for Canadian mothers and infants. Paediatr Child Health 2007, 12:589-93. CPS.
6. Greer FR. 25-Hydroxyvitamin D: functional outcomes in infants and young children. Am J Clin Nutr 2008, 88:529S-533S.
7. Greer FR. Defining vitamin D deficiency in children: beyond 25-OH vitamin D serum concentrations. Pediatrics 2009, 124:1471-3. 10.1542/peds.2009-2307, 19858159.
8. Litonjua AA. Childhood asthma may be a consequence of vitamin D deficiency. Curr Opin Allergy Clin Immunol 2009, 9:202-7. 10.1097/ACI.0b013e32832b36cd, 2897155, 19365260.
9. Holick MF. Vitamin D deficiency. N Engl J Med 2007, 357:266-81. 10.1056/NEJMra070553, 17634462.
10. Bouillon R. Vitamin D: From photosynthesis, metabolism, and action to clinical applications. Endocrinology 2001, 1009-28. Philadelphia: W.B. Saunders, DeGroot LJ, Jameson JL.
11. DeLuca HF. Overview of general physiologic features and functions of vitamin D. Am J Clin Nutr 2004, 80(Suppl):1689S-1696S.
12. MacLaughlin JA, Anderson RR, Holick MF. Spectral character of sunlight modulates photosynthesis of previtamin D3 and its photoisomers in human skin. Science 1982, 216:1001-3. 10.1126/science.6281884, 6281884.
13. Webb AR, Kline L, Holick MF. Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin. J Clin Endocrinol Metab 1988, 67:373-8. 10.1210/jcem-67-2-373, 2839537.
14. Behrman RK, Jenson HB R. Nelson Textbook of Pediatrics 2000, Philadelphia: W.B. Saunders Company, 16.
15. Roth DE, Martz P, Yeo R, Prosser C, Bell M, Jones AB. Are national vitamin D guidelines sufficient to maintain adequate blood levels in children?. Can J Public Health 2005, 96:443-9.
16. Health Canada Do Canadian children meet their nutrient requirements through food intake alone? 2007, http://www.hc-sc.gc.ca/fn-an/surveill/nutrition/commun/art-nutr-child-enf-eng.php#a33. 2007, Cat. H164-112, Health Canada.
17. Gordon CM, Feldman HA, Sinclair L, Williams AL, Kleinman PK, Perez-Rossello J, Cox JE. Prevalence of vitamin D deficiency among healthy infants and toddlers. Arch Pediatr Adolesc Med 2008, 162:505-12. 10.1001/archpedi.162.6.505, 3206624, 18524739.
18. Mansbach JM, Ginde AA, Camargo CA. Serum 25-hydroxyvitamin D levels among US children aged 1 to 11 years: do children need more vitamin D?. Pediatrics 2009, 124:1404-10. 10.1542/peds.2008-2041, 3765249, 19951983.
19. Kumar J, Muntner P, Kaskel FJ, Hailpern SM, Melamed ML. Prevalence and associations of 25-hydroxyvitamin D deficiency in US children: NHANES 2001-2004. Pediatrics 2009, 124:e362-70. 10.1542/peds.2009-0051, 3749840, 19661054.
20. Stoian CA, Lyon M, Cox RG, Stephure DK, Mah JK. Vitamin D concentrations among healthy children in Calgary, Alberta. Paediatr Child Health 2011, 16:82-6. 3043039, 22294867.
21. Hammer LD, Bryson S, Agras WS. Development of feeding practices during the first 5 years of life. Arch Pediatr Adolesc Med 1999, 153:189-94.
22. CPS Nutrition for Health Term Infants - Statement of the joint working group 2009, Canada: Canadian Paediatric Society, Dieticians of Canada and Health Canada, CPS.
23. Northstone K, Rogers I, Emmett P. Drinks consumed by 18-month-old children: are current recommendations being followed?. Eur J Clin Nutr 2002, 56:236-44. 10.1038/sj.ejcn.1601313, 11960299.
24. Korsch M, Nelson K, Reinhart J. Feeding behaviors in infancy and early childhood. Guidelines for Health Supervision III. Vol 50 1997, 57. American Academy of Pediatrics: Elk Grove Village, Ill.
25. Baker RD, Greer FR. Diagnosis and prevention of iron deficiency and iron-deficiency anemia in infants and young children (0-3 years of age). Pediatrics 2010, 126:1040-50. 10.1542/peds.2010-2576, 20923825.
26. Lips P. Vitamin D physiology. Prog Biophys Mol Biol 2006, 92:4-8. 10.1016/j.pbiomolbio.2006.02.016, 16563471.
27. Langlois K, Greene-Finestone L, Little J, Hidiroglou N, Whitting S. Vitamin D status of Canadians as measured in the 2007 to 2009 Canadian Health Measures Survey. Health Reports (Statistics Canada) 2010, 21:47-55.
28. Maguire JL, Birken C, Mamdani M, Thorpe KE, Parkin PC. How much cow's milk should preschoolers be drinking?: A TARGet Kids! study. Proceedings of the Pediatric Academic Societies Annual Meeting 2011, E-PAS-1385.5.
29. Maguire JL, Birken C, Mamdani M, Thorpe KE, Parkin PC. Milk volume, vitamin D supplementation, outdoor activity and season are important predictors of vitamin D serum level in preschoolers: A TARGet Kids! study. Proceedings of the Pediatric Academic Societies Annual Meeting 2011, E-PAS-2155.8.
30. Gessner BD, Plotnik J, Muth PT. 25-hydroxyvitamin D levels among healthy children in Alaska. J Pediatr 2003, 143:434-7. 10.1067/S0022-3476(03)00410-4, 14571215.
31. Gordon CM, DePeter KC, Feldman HA, Grace E, Emans SJ. Prevalence of vitamin D deficiency among healthy adolescents. Arch Pediatr Adolesc Med 2004, 158:531-7. 10.1001/archpedi.158.6.531, 15184215.
32. Newhook LA, Sloka S, Grant M, Randell E, Kovacs CS, Twells LK. Vitamin D insufficiency common in newborns, children and pregnant women living in Newfoundland and Labrador. Canada. Matern Child Nut 2009, 5:186-91.
33. Ward LM, Gaboury I, Ladhani M, Zlotkin S. Vitamin D-deficiency rickets among children in Canada. CMAJ 2007, 177:161-6. 10.1503/cmaj.061377, 1913133, 17600035.
34. Mallet E, Gugi B, Brunelle P, Henocq A, Basuyau JP, Lemeur H. Vitamin D supplementation in pregnancy: a controlled trial of two methods. Obstet Gynecol 1986, 68:300-4. 10.1097/00006250-198609000-00002, 3755517.
35. Javaid MK, Crozier SR, Harvey NC, Gale CR, Dennison EM, Boucher BJ, Arden NK, Godfrey KM, Cooper C, Princess Anne Hospital Study Group Maternal vitamin D status during pregnancy and childhood bone mass at age 9 years: a longitudinal study. Lancet 2006, 367:36-43. 10.1016/S0140-6736(06)67922-1, 16399151, Princess Anne Hospital Study Group.
36. Markestad T, Aksnes L, Ulstein M, Aarskog D. 25-Hydroxyvitamin D and 1,25-dihydroxyvitamin D of D2 and D3 origin in maternal and umbilical cord serum after vitamin D2 supplementation in human pregnancy. Am J Clin Nutr 1984, 40:1057-63.
37. Lee JM, Smith JR, Philipp BL, Chen TC, Mathieu J, Holick MF. Vitamin D deficiency in a healthy group of mothers and newborn infants. Clin Pediatr (Phila) 2007, 46:42-4. 10.1177/0009922806289311, 17164508.
38. Hollis BW, Pittard WB. Evaluation of the total fetomaternal vitamin D relationships at term: evidence for racial differences. J Clin Endocrinol Metab 1984, 59:652-7. 10.1210/jcem-59-4-652, 6090493.
39. Bianchi ML. Osteoporosis in children and adolescents. Bone 2007, 41:486-95. 10.1016/j.bone.2007.07.008, 17706477.
40. Hypponen E, Laara E, Reunanen A, Jarvelin MR, Virtanen SM. Intake of vitamin D and risk of type 1 diabetes: a birth-cohort study. Lancet 2001, 358:1500-3. 10.1016/S0140-6736(01)06580-1, 11705562.
41. Zipitis CS, Akobeng AK. Vitamin D supplementation in early childhood and risk of type 1 diabetes: a systematic review and meta-analysis. Arch Dis Child 2008, 93:512-7. 10.1136/adc.2007.128579, 18339654.
42. Heikkinen T, Jarvinen A. The common cold. Lancet 2003, 361:51-9. 10.1016/S0140-6736(03)12162-9, 12517470.
43. Burt CW, McCaig LF, Rechtsteiner EA. Ambulatory medical care utilization estimates for. Adv Data 2005, 2007:1-15.
44. Lambert SB, Allen KM, Druce JD, Birch CJ, Mackay IM, Carlin JB, Carapetis JR, Sloots TP, Nissen MD, Nolan TM. Community epidemiology of human metapneumovirus, human coronavirus NL63, and other respiratory viruses in healthy preschool-aged children using parent-collected specimens. Pediatrics 2007, 120:e929-37. 10.1542/peds.2006-3703, 17875651.
45. Lambert SB, Allen KM, Carter RC, Nolan TM. The cost of community-managed viral respiratory illnesses in a cohort of healthy preschool-aged children. Respir Res 2008, 9:11. 10.1186/1465-9921-9-11, 2266731, 18215329.
46. Collet JP, Burtin P, Kramer MS, Floret D, Bossard N, Ducruet T. Type of day-care setting and risk of repeated infections. Pediatrics 1994, 94:997-9.
47. Schwartz B, Giebink GS, Henderson FW, Reichler MR, Jereb J, Collet JP. Respiratory infections in day care. Pediatrics 1994, 94:1018-20.
48. Benediktsdottir B. Upper airway infections in preschool children-frequency and risk factors. Scand J Prim Health Care 1993, 11:197-201. 10.3109/02813439308994830, 8272652.
49. Kvaerner KJ, Nafstad P, Jaakkola JJ. Upper respiratory morbidity in preschool children: a cross-sectional study. Arch Otolaryngol Head Neck Surg 2000, 126:1201-6. 10.1001/archotol.126.10.1201, 11031406.
50. Chonmaitree T, Revai K, Grady JJ, Clos A, Patel JA, Nair S, Fan J, Henrickson KJ. Viral upper respiratory tract infection and otitis media complication in young children. Clin Infect Dis 2008, 46:815-23. 10.1086/528685, 2744371, 18279042.
51. Carabin H, Gyorkos TW, Soto JC, Penrod J, Joseph L, Collet JP. Estimation of direct and indirect costs because of common infections in toddlers attending day care centers. Pediatrics 1999, 103:556-64. 10.1542/peds.103.3.556, 10049956.
52. Haskins R. Acute illness in day care: how much does it cost?. Bull N Y Acad Med 1989, 65:319-43. 1807808, 2686785.
53. Hope-Simpson RE. The Transmission of Epidemic Influenza 1992, New York: Plenum Press.
54. Cannell JJ, Vieth R, Umhau JC, Holick MF, Grant WB, Madronich S, Garland CF, Giovannucci E. Epidemic influenza and vitamin D. Epidemiol Infect 2006, 134:1129-40. 10.1017/S0950268806007175, 2870528, 16959053.
55. Herr C, Shaykhiev R, Bals R. The role of cathelicidin and defensins in pulmonary inflammatory diseases. Expert Opin Biol Ther 2007, 7:1449-61. 10.1517/14712598.7.9.1449, 17727333.
56. Bartley J. Vitamin D, innate immunity and upper respiratory tract infection. J Laryngol Otol 2010, 124:465-9.
57. Hansdottir S, Monick MM, Hinde SL, Lovan N, Look DC, Hunninghake GW. Respiratory epithelial cells convert inactive vitamin D to its active form: potential effects on host defense. J Immunol 2008, 181:7090-9. 2596683, 18981129.
58. Diamond G, Legarda D, Ryan LK. The innate immune response of the respiratory epithelium. Immunol Rev 2000, 173:27-38. 10.1034/j.1600-065X.2000.917304.x, 10719665.
59. Brogden KA. Antimicrobial peptides: pore formers or metabolic inhibitors in bacteria?. Nat Rev Microbiol 2005, 3:238-50. 10.1038/nrmicro1098, 15703760.
60. Liu PT, Stenger S, Li H, Wenzel L, Tan BH, Krutzik SR, Ochoa MT, Schauber J, Wu K, Meinken C, Kamen DL, Wagner M, Bals R, Steinmeyer A, Zügel U, Gallo RL, Eisenberg D, Hewison M, Hollis BW, Adams JS, Bloom BR, Modlin RL. Toll-like receptor triggering of a vitamin D-mediated human antimicrobial response. Science 2006, 311:1770-3. 10.1126/science.1123933, 16497887.
61. Gombart AF, Borregaard N, Koeffler HP. Human cathelicidin antimicrobial peptide (CAMP) gene is a direct target of the vitamin D receptor and is strongly up-regulated in myeloid cells by 1,25-dihydroxyvitamin D3. FASEB J 2005, 19:1067-77. 10.1096/fj.04-3284com, 15985530.
62. Aloia JF, Talwar SA, Pollack S, Yeh J. A randomized controlled trial of vitamin D3 supplementation in African American women. Arch Intern Med 2005, 165:1618-23. 10.1001/archinte.165.14.1618, 1464166, 16043680.
63. Ginde AA, Mansbach JM, Camargo CA. Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey. Arch Intern Med 2009, 169:384-90. 10.1001/archinternmed.2008.560, 3447082, 19237723.
64. Laaksi I, Ruohola JP, Tuohimaa P, Auvinen A, Haataja R, Pihlajamaki H, Ylikomi T. An association of serum vitamin D concentrations < 40 nmol/L with acute respiratory tract infection in young Finnish men. Am J Clin Nutr 2007, 86:714-7.
65. Sabetta JR, DePetrillo P, Cipriani RJ, Smardin J, Burns LA, Landry ML. Serum 25-hydroxyvitamin d and the incidence of acute viral respiratory tract infections in healthy adults. PLoS One 2010, 5:e11088. 10.1371/journal.pone.0011088, 2885414, 20559424.
66. Camargo CA, Ingham T, Wickens K. Cord blood 25-hydroxyvitamin D levels and risk of childhood wheeze in New Zealand [abstract]. Am J Respir Crit Care Med 2008, 177(Suppl):A993.
67. Li-Ng M, Aloia JF, Pollack S, Cunha BA, Mikhail M, Yeh J, Berbari N. A randomized controlled trial of vitamin D3 supplementation for the prevention of symptomatic upper respiratory tract infections. Epidemiol Infect 2009, 137:1396-1404. 10.1017/S0950268809002404, 19296870.
68. Laaksi I, Ruohola JP, Mattila V, Auvinen A, Ylikomi T, Pihlajamaki H. Vitamin D supplementation for the prevention of acute respiratory tract infection: a randomized, double-blinded trial among young Finnish men. J Infect Dis 2010, 202:809-14. 10.1086/654881, 20632889.
69. Urashima M, Segawa T, Okazaki M, Kurihara M, Wada Y, Ida H. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr 2010, 91:1255-60. 10.3945/ajcn.2009.29094, 20219962.
70. HealthCanada. Vitamin D Recommendations and review status 2010, http://www.hc-sc.gc.ca/fn-an/nutrition/vitamin/vita-d-eng.php. Accessed January 5, 2010, HealthCanada. Vitamin D.
71. To T, Gershon A, Tassoudji M. ICES Investigative Report: The Burden of Asthma in Ontario 2006, Toronto: Institute for Clinical Evaluative Sciences.
72. CIHI Respiratory disease in Canada 2001, Ottawa: Canadian Institute for Health Information: Canadian Lung Association, Statistics Canada, CIHI.
73. ICES Research Atlas: Inpatient and day surgery use by children in Ontario 1998, Toronto: Institute for Clinical Evaluative Sciences, ICES.
74. Krahn MD, Berka C, Langlois P, Detsky AS. Direct and indirect costs of asthma in Canada, 1990. CMAJ 1996, 154:821-31. 1487808, 8634960.
75. Litonjua AA, Weiss ST. Is vitamin D deficiency to blame for the asthma epidemic?. J Allergy Clin Immunol 2007, 120:1031-5. 10.1016/j.jaci.2007.08.028, 17919705.
76. Masoli M, Fabian D, Holt S, Beasley R. The global burden of asthma: executive summary of the GINA Dissemination Committee report. Allergy 2004, 59:469-78. 10.1111/j.1398-9995.2004.00526.x, 15080825.
77. Bosse Y, Maghni K, Hudson TJ. 1alpha,25-dihydroxy-vitamin D3 stimulation of bronchial smooth muscle cells induces autocrine, contractility, and remodeling processes. Physiol Genomics 2007, 29:161-8.
78. Song Y, Qi H, Wu C. Effect of 1,25-(OH)2D3 (a vitamin D analogue) on passively sensitized human airway smooth muscle cells. Respirology 2007, 12:486-94. 10.1111/j.1440-1843.2007.01099.x, 17587413.
79. Raby BA, Lazarus R, Silverman EK, Lake S, Lange C, Wjst M, Weiss ST. Association of vitamin D receptor gene polymorphisms with childhood and adult asthma. Am J Respir Crit Care Med 2004, 170:1057-65. 10.1164/rccm.200404-447OC, 15282200.
80. Saadi A, Gao G, Li H, Wei C, Gong Y, Liu Q. Association study between vitamin D receptor gene polymorphisms and asthma in the Chinese Han population: a case-control study. BMC Med Genet 2009, 10:71. 2720948, 19622139.
81. Bosse Y, Lemire M, Poon AH, Daley D, He JQ, Sandford A, White JH, James AL, Musk AW, Palmer LJ, Raby BA, Weiss ST, Kozyrskyj AL, Becker A, Hudson TJ, Laprise C. Asthma and genes encoding components of the vitamin D pathway. Respir Res 2009, 10:98. 10.1186/1465-9921-10-98, 2779188, 19852851.
82. Black PN, Scragg R. Relationship between serum 25-hydroxyvitamin d and pulmonary function in the third national health and nutrition examination survey. Chest 2005, 128:3792-8. 10.1378/chest.128.6.3792, 16354847.
83. Brehm JM, Schuemann B, Fuhlbrigge AL, Hollis BW, Strunk RC, Zeiger RS, Weiss ST, Litonjua AA, Childhood Asthma Management Program Research Group Serum vitamin D levels and severe asthma exacerbations in the Childhood Asthma Management Program study. J Allergy Clin Immunol 2010, 126:52-8 e55. 10.1016/j.jaci.2010.03.043, 2902692, 20538327, Childhood Asthma Management Program Research Group.
84. Searing DA, Zhang Y, Murphy JR, Hauk PJ, Goleva E, Leung DY. Decreased serum vitamin D levels in children with asthma are associated with increased corticosteroid use. J Allergy Clin Immunol 2010, 125:995-1000. 10.1016/j.jaci.2010.03.008, 2866800, 20381849.
85. Brehm JM, Celedon JC, Soto-Quiros ME, Avila L, Hunninghake GM, Forno E, Laskey D, Sylvia JS, Hollis BW, Weiss ST, Litonjua AA. Serum vitamin D levels and markers of severity of childhood asthma in Costa Rica. Am J Respir Crit Care Med 2009, 179:765-71. 10.1164/rccm.200808-1361OC, 2675563, 19179486.
86. StatsCan Canadian Community Health Survey 2010, Available online: http://www.statcan.gc.ca/concepts/health-sante/content-contenu-eng.htm Accessed January 5, 2010, StatsCan.
87. Thorpe KE, Zwarenstein M, Oxman AD, Treweek S, Furberg CD, Altman DG, Tunis S, Bergel E, Harvey I, Magid DJ, Chalkidou K. A pragmatic-explanatory continuum indicator summary (PRECIS): a tool to help trial designers. CMAJ 2009, 180:E47-E57. This article was published simultaneously in the May 2009 issue of the J Clin Epidemiol www.jclinepi.com, 10.1503/cmaj.090523, 2679824, 19372436.
88. Chan AW, Tetzlaff JM, Gøtzsche PC, Altman DG, Mann H, Berlin JA, Dickersin K, Hróbjartsson A, Schulz KF, Parulekar WR, Krleža-Jeric K, Laupacis A, Moher D. SPIRIT 2013 explanation and elaboration: guidance for protocols of clinical trials. BMJ 2013, 346:e7586. 10.1136/bmj.e7586, 3541470, 23303884.
89. Chan AW, Tetzlaff J, Altman DG, Gøtzsche PC, Horobjartsson A. The Spirit Initiative: Defining Standard Protocol Items for Randomized Trials. Enhancing the Quality and Transparency of Health Research 2010, http://www.equator-network.org/resource-centre/library-of-health-research-reporting/reporting-guidelines-under-development/reporting-guidelines-under-development/. Accessed September 6, 2010.
90. Schulz KF, Altman DG, Moher D, CONSORT Group CONSORT 2010 Statement: updated guidelines for reporting parallel group randomised trials. BMJ 2010, 340:c332. 10.1136/bmj.c332, 2844940, 20332509, CONSORT Group.
91. Barger-Lux MJ, Heaney RP, Dowell S, Chen TC, Holick MF. Vitamin D and its major metabolites: serum levels after graded oral dosing in healthy men. Osteoporos Int 1998, 8:222-30. 10.1007/s001980050058, 9797906.
92. Aloia JF, Talwar SA, Pollack S, Feuerman M, Yeh JK. Optimal vitamin D status and serum parathyroid hormone concentrations in African American women. Am J Clin Nutr 2006, 84:602-9. 2777656, 16960175.
93. PHAC Respiratory virus surveillance 2010, http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/01vol27/dr2711eb.html. Accessed August 22, 2010, PHAC.
94. Haynes RB, Dantes R. Patient compliance and the conduct and interpretation of therapeutic trials. Control Clin Trials 1987, 8:12-9. 10.1016/0197-2456(87)90021-3, 3568692.
95. Call SA, Vollenweider MA, Hornung CA, Simel DL, McKinney WP. Does this patient have influenza?. JAMA 2005, 293:987-97. 10.1001/jama.293.8.987, 15728170.
96. King JC, Stoddard JJ, Gaglani MJ, Moore KA, Magder L, McClure E, Rubin JD, Englund JA, Neuzik K. Effectiveness of school-based influenza vaccination. N Engl J Med 2006, 355:2523-32. 10.1056/NEJMoa055414, 17167135.
97. Esposito S, Molteni CG, Daleno C, Valzano A, Tagliabue C, Galeone C, Milani G, Fossali E, Marchisio P, Principi N. Collection by trained pediatricians or parents of mid-turbinate nasal flocked swabs for the detection of influenza viruses in childhood. Virol J 2010, 7:85. 10.1186/1743-422X-7-85, 2873380, 20433729.
98. Lambert SB, Allen KM, Nolan TM. Parent-collected respiratory specimens-a novel method for respiratory virus and vaccine efficacy research. Vaccine 2008, 26:1826-31. 10.1016/j.vaccine.2008.01.055, 18329758.
99. Templeton KE, Scheltinga SA, Beersma MF, Kroes AC, Claas EC. Rapid and sensitive method using multiplex real-time PCR for diagnosis of infections by influenza a and influenza B viruses, respiratory syncytial virus, and parainfluenza viruses 1, 2, 3, and 4. J Clin Microbiol 2004, 42:1564-9. 10.1128/JCM.42.4.1564-1569.2004, 387552, 15071005.
100. Mahony J, Chong S. Clinical evaluation of a new ID-Tag RVP assay for the detection of 20 respiratory viruses. Clin Microbiol Infect 2007, 1732:224.
101. Jacobs B, Young NL, Dick PT, Ipp MM, Dutkowski R, Davies HD, Langley JM, Greenberg S, Stephens D, Wang EE. Canadian Acute Respiratory Illness and Flu Scale (CARIFS): development of a valid measure for childhood respiratory infections. J Clin Epidemiol 2000, 53:793-9. 10.1016/S0895-4356(99)00238-3, 10942861.
102. Belshe RB, Mendelman PM, Treanor J, King J, Gruber WC, Piedra P, Bernstein DI, Hayden FG, Kotloff K, Zangwill K, Iacuzio D, Wolff M. The efficacy of live attenuated, cold-adapted, trivalent, intranasal influenzavirus vaccine in children. N Engl J Med 1998, 338:1405-12. 10.1056/NEJM199805143382002, 9580647.
103. Asher MI, Keil U, Anderson HR, Beasley R, Crane J, Martinez F, Mitchell EA, Pearce N, Sibbald B, Stewart AW. International Study of Asthma and Allergies in Childhood (ISAAC): rationale and methods. Eur Respir J Mar 1995, 8:483-91.
104. Singh RJ, Taylor RL, Reddy GS, Grebe SK. C-3 epimers can account for a significant proportion of total circulating 25-hydroxyvitamin D in infants, complicating accurate measurement and interpretation of vitamin D status. J Clin Endocrinol Metab 2006, 91:3055-61. 10.1210/jc.2006-0710, 16720650.
105. DiaSorin The Diagnostic Specialist 2010, http://www.diasorin.com/en/productsandsystems/view/20 Accessed September 6, 2010, DiaSorin.
106. Carter GD, Carter R, Jones J, Berry J. How accurate are assays for 25-hydroxyvitamin D? Data from the international vitamin D external quality assessment scheme. Clin Chem 2004, 50:2195-7. 10.1373/clinchem.2004.040683, 15375018.
107. Morinis J, Maguire J, Khovratovich M, McCrindle BW, Parkin PC, Birken CS. Paediatric obesity research in early childhood and the primary care setting: The TARGet Kids! research network. Int J Environ Res Public Health 2012, 9:1343-54. 10.3390/ijerph9041343, 3366615, 22690197.
108. Gozdzik A, Barta JL, Weir A, Cole DE, Vieth R, Whiting SJ, Parra EJ. Serum 25-hydroxyvitamin D concentrations fluctuate seasonally in young adults of diverse ancestry living in Toronto. J Nutr 2010, 140:2213-20. 10.3945/jn.110.126284, 20980651.
109. Shriver MD, Parra EJ. Comparison of narrow-band reflectance spectroscopy and tristimulus colorimetry for measurements of skin and hair color in persons of different biological ancestry. Am J Phys Anthropol 2000, 112:17-27. 10.1002/(SICI)1096-8644(200005)112:1<17::AID-AJPA3>3.0.CO;2-D, 10766940.
110. Clarys P, Alewaeters K, Lambrecht R, Barel AO. Skin color measurements: comparison between three instruments: the Chromameter(R), the DermaSpectrometer(R) and the Mexameter(R). Skin Res Technol 2000, 6:230-8. 10.1034/j.1600-0846.2000.006004230.x, 11428962.
111. Hunter S, Wells KJ, Jacobsen PB. Assessment of elementary school students' sun protection behaviors. Pediatr Dermatol 2010, 27:182-8. 10.1111/j.1525-1470.2009.00940.x, 3683831, 19686304.
112. Maguire JL, Birken CS, Jacobson S, Peer M, Taylor C, Kambalia A, Mekky M, Thorpe K, Parkin PC. Office-based intervention to reduce bottle use among toddlers: TARGet Kids! pragmatic, randomized trial. Pediatrics 2010, 126:e343-50. 10.1542/peds.2009-3583, 20624802.
113. Fisher LD, Dixon DO, Herson J, Frankowski RK, Hearron MS, Peace KE. Intention to treat in clinical trials. Statistical issues in drug research and development 1990, New York: Marcel Dekker.
114. Andersen PK, Gill RD. Cox's regression model for counting processes: A large sample study. Ann Statist 1982, 10:1100-20.
115. Fendrick AM, Monto AS, Nightengale B, Sarnes M. The economic burden of non-influenza-related viral respiratory tract infection in the United States. Arch Intern Med 2003, 163:487-94. 10.1001/archinte.163.4.487, 12588210.
116. Hoch JS. Improving efficiency and value in palliative care with net benefit regression: an introduction to a simple method for cost-effectiveness analysis with person-level data. J Pain Symptom Manage 2009, 38:54-61. 10.1016/j.jpainsymman.2009.04.010, 19615627.
117. Hoch JS, Briggs AH, Willan AR. Something old, something new, something borrowed, something blue: a framework for the marriage of health econometrics and cost-effectiveness analysis. Health Econ 2002, 11:415-30. 10.1002/hec.678, 12112491.
118. Gordon CM, Williams AL, Feldman HA, May J, Sinclair L, Vasquez A, Cox JE. Treatment of hypovitaminosis D in infants and toddlers. J Clin Endocrinol Metab 2008, 93:2716-21. 10.1210/jc.2007-2790, 2729207, 18413426.
119. Tau C, Ciriani V, Scaiola E, Acuna M. Twice single doses of 100,000 IU of vitamin D in winter is adequate and safe for prevention of vitamin D deficiency in healthy children from Ushuaia, Tierra Del Fuego, Argentina. J Steroid Biochem Mol Biol 2007, 103:651-4. 10.1016/j.jsbmb.2006.12.027, 17257830.
120. Vieth R. Vitamin D toxicity, policy, and science. J Bone Miner Res 2007, 22(Suppl 2):V64-8.
121. Vieth R. Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. Am J Clin Nutr 1999, 69:842-56.